Fig. 4. CD4⁺ T cell phenotypic differences between non-hospitalized and previously hospitalized patients.

(A) Comparison of timing of sample collection of non-hospitalized (n = 15) and previously hospitalized (n = 8) subjects for phenotypic comparisons. (B) Representative PD-1 x CXCR5 staining (top row) and CXCR3 x CCR4 staining (bottom row) of live CD4⁺ T cell events. The left column represents an example of a non-hospitalized subject with combined tetramer⁺ (bound fraction, black) and tetramer^– bulk CD4⁺ (unbound fraction, light gray) gated cells. The right column represents a previously hospitalized subject with combined tetramer⁺ (bound fraction, red) and tetramer^– bulk CD4⁺ (unbound fraction, dark gray) gated cells. (C) Percentages of PD-1^hiCXC5⁺, CXCR5⁺, CXCR3⁺CCR4^–, and CXCR3^–CCR4⁺ cells within combined tetramer⁺ and bulk (tetramer^–) CD4⁺ T cells from non-hospitalized and previously hospitalized subjects. Horizontal lines indicate median values. Statistics by Mann-Whitney tests. *p < 0.05, **p < 0.01. ns = not statistically significant. (D-G) Scatter plots illustrating changes in combined tetramer⁺ PD-1^hiCXC5⁺ (D), CXCR5⁺ (E), CXCR3⁺CCR4^– (F), and CXCR3^–CCR4⁺ (G) cells per million CD4⁺ T cells over time. Lines connect datapoints from the same subjects.